I would suggest that setting up the rewinding fixture (I wouldn't
suggest doing these by hand) and dismantling and reassembling the valve
so the coil can be rewound, plus the expense of good quality magnet
wire, would be far more work and money than just purchasing the correct
valves. You can probably trade in yours, or auction them at eBay.
David Dewey - who rewinds toy train armatures with aerospace magnet
wire (but just as a hobby!)